This Ain't It Chief. This aint it expresses disagreement. However there are quite a few.
On That Ragnarok Shit 5. In fact it only showed up once on Twitter before 2014. Twisted Transistor Korn cover 4.
The phrase is used in a playfully insulting way in the similar vein of the phrase Imma Keep It Real With U Chief.
Strawberries on Pizza are to die for. And chief like boss is a chummy but patronizing way to address someone. This a hit chief Yeah said this a hit yeah huh uh Yeah yeah yeah Verse 1. This aint it chief.